In conventional automatic analyzing apparatuses, a specimen is sucked from a sample container and is introduced to a well on a plate or a measurement cell, a measurement is performed by fluorescence or spectroscopy, and the concentration of the specimen is detected. In the automatic analyzing apparatuses, it is required to increase the sensitivity of the measurement.
One of the fields in which an analysis with highly-sensitive detection is required is a measurement of the concentration of a prostate specific antigen (PSA) in blood. The measurement of the concentration of the prostate specific antigen in blood is promising with regard to the diagnosis of prostate cancer. Patent Literature 1 discloses one example of the measurement.
In Patent Literature 1, after an 8A6 monoclonal antibody is immobilized on magnetic beads, the magnetic beads are injected into each well on a plate. Then blocking is performed according to a procedure of a sandwich ELISA method, and an HYB4 monoclonal antibody, which is a primary antibody, is added and the obtained solution is mixed into an analyte. After that, a fluorochrome-labeled antibody is added and the resulting solution is left at room temperature. Then the plate is subjected to flow cytometry to detect fluorescence.